Daniel e



(No Model.)

D. R. HART.

SCREW DRIVER. No. 370,255. Patented Sept. 20, 1887.

ihvirnn STATES ATENT Fries.

DANIEL a. HART, on NEW YORK, N. Y.

SCREW-DRIVER.

SPECIFICATION forming part of Letters Patent No. 370,255, datedSeptember 20, 1887.

Application filed June 23, 1887.

To aZZ whom it may concern.-

Be it known that I, DANIEL R. HART, of the city, county, and State ofNew York, have invented a new and useful Improvement in Screw-Drivers,of which the following is a specification, reference being had to theaccompanying drawings, forming part thereof.

My invention relates to a screw-driver for inserting screws in wood andother material 5 and it consists in a novel construction of such toolwhereby I am enabled to insert screws much more easily and effectivelythan has heretofore been done.

Heretofore considerable difficulty has been experienced by mechanics andothers in inserting screws by the use of the ordinary screw-driver.After considerable thought and experiment I have found the cause of thesaid difficulty, and have also invented means by which it is avoided.

In manufacturing the ordinary screw, and which is intended moreparticularly for use in wood, one of the steps is to mill the head ofthe screw so as to form a slot or nick therein to allow of the insertionof the driver. I have discovered that the result of the milling is,among other things, to make the bottom of the slot ofa concave form byreason of the circular form of the millingcutter, so that when theordinary screw-driver is inserted in the slot such driver, which isstraight at the point, instead of bearing against the whole length ofthe bottom of the slot, bears only upon the extremities thereof. Anotherdefect in the said driver is the tapering or wedge-shaped form of thoseportions of the sides thereof which enter the slot of the screw-head. Inpractice serious consequences follow the use of such driver on saidscrews. For example, when the driver is forced against the screw ittends to spread or split the head thereof, for the reason that thedrivers wedge-shaped form tends to prevent its insertion sufficient] yto touch the lower portion of the walls of the slot, and thereforecauses it to act upon the upper portion of said walls,and thereby give aragged and uneven appearance to the slot. More particularly is this thecase when the screws have been highly finished or plated. Besides, thesaid wedge-shapedpointof the driver will tend to cause it to rise outoftheslot when press- Serial No. 242,244. (No model.)

ore is applied to turn the screw. Another difficulty with the ordinaryscrew-driver is its tendency to slip from the slot sidewise while beingused, especially when the screw to beinserted is in such a positionas,for instance, in a corner-that the operator is required to hold thescrew-driver at an angle or out of alignment with the screw.

My invention has for its object the obviation of the difficultiesmentioned; and it consists, first, in constructing the bottom of thescrew-driver in such form that when fully inserted in the slot of thescrew-head itwill bear against all parts of the bottom of the slot,and,secondly, in making those portions of the sides of the screw-driverwhich enter the slot of the screw-head slightly tapering, being thickestat the point, by the use of which said invention the operator is enabledto easily and effectively insert screws wherever desired.

In the drawings, Figure 1 represents a front view of a hand screw-driverconstructed according to my invention. Fig. 2 is asideview of aportionofthe same. Fig. 3 is a front view of a screw-driver bit adapted to beused in a bit-stock; and Fig. 4 is a side view of an ordinarywood-screw, a portion being broken away to show the slot.

a designates an ordinary wood-screw,having a head portion, 1), providedwith a slot, 0, to receive the screw-driver,

(Z is a screw-driver,provided with a handle, 6, and having itspointfmadein convex form,

so as to correspond with and fit upon the concave or arc-shaped bottomof the slot 0. The sides of that portion of the screw-driver whichengages with the slot are made to taper slightly in thickness from thepoint f, having less thickness at the part 9 than'at the point f. Bythis construction the screw-drivenwhcn inserted in the slot 0, will acton the lower or base portion of the walls of the slot, therebypreserving the upper and exposed edges of the slot from injury whileinserting the screw.

By my invention a screw-driver, while inserting a screw, cannot slip outof the slot, since the concave form of the bottom of the latter preventsthe pointf moving sidewise in the slot when pressure is applied to turnthe screw. A screw-driver formed with tapering sides, as described, willbe prevented from ris ing in the slot when pressure is applied to turnit, and will also act on the lower portions of the walls of the slot,thus preserving the exposed edges thereof and avoiding'spreading and fitthe concave form of the bottoms of screw-head slots, substantially asdescribed.

' 2. A screw-driver having its point or front end made in convex form tocorrespond with and fit the concave form of the bottoms of screw-headslots, and having those portions of its sides adaptedflfor entering saidslots 2o tapering in thickness, substantially as described,

DANIEL R. HART.

Witnesses: 7

JAMES S. GREVES, PHILIP J. OREILLY.

